Confinement driven effects in a room temperature ferroelectric liquid crystal: X-ray, linear and non-linear dielectric investigations

Abstract

We present results of X-ray, linear and non-linear dielectric constant measurements on a room temperature ferroelectric liquid crystalline phase in its bulk form and upon confinement in an Anopore membrane. The used material exhibits smectic C* (SmC*) helical pitch of p ≅ 200 nm, which is comparable to the pore dimension of the membrane. X-ray measurements show several interesting results including unusually strong harmonic reflections, substantial broadening of the peak profile, correlation length smaller than the pore diameter, etc. The data suggest that the smectic A–SmC* transition could be very close to a tricritical point in the bulk and moving away from it upon confinement. The dielectric studies show that confinement accelerates the relaxation dynamics of both the soft and the Goldstone modes, although with a reduced strength. The non-linear component of the dielectric constant exhibits qualitatively different thermal behaviour in the bulk and Anopore samples.